Two Senate Democrats unveiled a plan Tuesday that would require automakers to share more information about fatal accidents in an effort to help federal regulators uncover defects such as the flawed General Motors ignition switch that has been linked to at least 12 deaths.

GM has said it knew about the defective switch for more than a decade before initiating a recall last month of 1.6 million Chevrolet Cobalts and five other small models. The National Highway Traffic Safety Administration had been looking into the defect for years but has said it did not have enough information to order a recall.

The legislation by Sens. Richard Blumenthal (D-Conn.) and Edward J. Markey (D-Mass.) would require automakers to routinely submit accident reports or other documents to the NHTSA when they learned of a fatality involving one of their vehicles.

The bill would require the NHTSA, in turn, to make the information available to the public in a user-friendly, searchable database. That would allow consumers and watchdog groups to more easily sift through the data in search of safety problems.

“A massive information breakdown at NHTSA has led to deadly vehicle breakdowns on our roads,” Markey said in a statement. “The Department of Transportation has the authority to require critical safety information be made publicly available, but it has never used its authority.”

The bill is intended to bolster the NHTSA’s Early Warning Reporting system, which contains death and injury reports that automakers submit to regulators when a defect is suspected. Under the legislation, that system would be automatically cross-referenced with a separate database that contains information from other sources, including police reports, about fatal accidents.

The NHTSA currently collects and maintains much of this data, but consumer advocates say the agency’s Web site is difficult to navigate and search. That makes it hard to connect the dots and identify a potential problem.

Markey tried in 2010 to make more information about highway fatalities available on the NHTSA’s Web site, but that measure did not clear Congress.

The new measure comes amid a host of government probes into GM’s handling of the ignition-switch defect, including a criminal investigation by federal prosecutors and inquiries by committees in the House and the Senate.

Meanwhile, GM is facing a growing number of lawsuits connected to the recall, which centers on an ignition switch that, when jostled or weighed down, can inadvertently turn the car off, disabling its electronic components, including the air bags.

A suit filed Monday in federal court in San Francisco alleges that GM’s plan to replace the ignition switches in its recall is insufficient. “To fully remedy the problem and render the defective vehicles safe and of economic value to their owners again, additional design elements beyond a new ignition switch are needed,” said the proposed class action, brought by a coalition of law firms, including Grant & Eisenhofer.

The suit — which seeks compensation for car owners who say they were defrauded because they bought Cobalts and other recalled models without knowledge of the defect — also alleges that in 2004, a GM engineer wrote that the troublesome ignition switch represented a “basic design flaw.”

After that, the suit alleges, GM engineers presented several fixes for the problem, but they were never implemented.

“We intend to show that despite the option of a straightforward fix, GM chose to dismiss the solution because of the added costs involved in undertaking a voluntary recall,” Adam Levitt, a director of Grant & Eisenhofer, said in a statement.

On Tuesday, GM chief executive Mary T. Barra is expected to testify on the matter before the House Energy and Commerce Committee. In the Senate, the commerce committee’s subpanel on consumer protection, which is chaired by Sen. Claire McCaskill (D-Mo.), is planning a hearing for later in April.

Michael A. Fletcher is a national economics correspondent, writing about unemployment, state and municipal debt, the evolving job market and the auto industry.

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